Full data are to be unveiled at an upcoming medical conference, AZ said, but did also reveal that, in addition to PFS, the objective response rate, disease control rate and duration of response also achieved clinically meaningful improvement versus chemotherapy, while the drug's safety profile was also consistent with earlier findings.

AZ said that its drug, once-daily pill, has been through one of the fastest development programmes ever - from start of clinical trials to approval in just over two and a half years.

It is cleared in the US, EU, Japan, Canada, Switzerland, Israel and Mexico as the first treatment for patients with EGFR T790M mutation-positive advanced NSCLC, with eligibility for treatment dependent on confirmation that the EGFR T790M mutation is present in the tumour.

In Europe, Tagrisso was the new first medicine to win clearance under the European Commission's expedited process, after Phase II studies showed an objective response rate of 66 percent and median progression-free survival of 9.7 months.